Commercial energy storage has moved from the margins to the mainstream as it fosters flexibility in our smarter, increasingly integrated energy systems. Natural gas has been identified by many as the fuel to take us to the no-carbon horizon; where a hydrogen economy waits on development. These two actors are already connected in precursor applications as transitional solutions for hydrogen handling and transportation are sought ahead of a fully established hydrogen infrastructure. This monograph explores some of leading advances in methane and hydrogen storage as well as the interesting link between these two important elements in our evolving energy system mosaic. Topics covered include: hydrogen absorption for storage; power-to-gas for energy system integration and storage; methanation for power-to-gas applications; production of hydrogen from methane decarbonisation into power to gas scenarios; power-to-gas in an ancillary service market; methane in MOFs: where, why and how; thermal management as a key in storing adsorbed natural gas; and gas hydrate potential and development for methane storage.

Energy has always been the driving force in the technological and economic development of societies. The consumption of a significant amount of energy is required to provide basic living conditions of developed countries (heating, transportation, lighting, etc.). Today's energy supply has a considerable impact on the environment, since it is fuelled by the burning of fossil fuels. In addition to this, the fossil fuel reserves are decreasing while the demand for energy is rapidly rising. Climate change, the depletion and geographical segregation of fossil fuel resources, health related issues as well as energy poverty constitute the driving forces towards the pursuit of alternative energy sources. In addition, countries with no access to oil reserves are being dependent from other countries for their energy supply, with a strong impact on politics and financial issues. But apart from occasional financial recessions, the long-term need for increasing amounts of energy as countries develop will become a major rate limiting step in the growth of the world economy [1]. The last years there is an on-going research on alternative fuels in order to overcome the fossil energy dependence and to provide a sustainable growth of economies and societies.

There continues to be growing interest in the development of PtG technology to provide energy storage, ancillary services and to provide cleanly produced hydrogen fuel for future generations of vehicles. To grow the industry, continuing research will be undertaken into using Cap-and-Trade or carbon taxes to provide financial incentives; utilizing green hydrogen for emissions savings in the production of petroleum and other products; the utilization of electrolysis systems to provide ancillary services to grid operators; and the use of the NG infrastructure to provide the long-term bulk storage needed to manage excess base load and integrate renewable power sources.

Methane can be produced via CO and CO2 methanation. However, the CO2 methanation is more relevant in the context of Power-to-Gas (PtG) applications. The two methanation reactions are accompanied by further reactions such as the reverse water gas shift reaction and the Boudouard reaction. Looking at the overall stoichiometry the CO2 methanation can be seen as the combination of the CO methanation with the reverse water-gas shift. The Boudouard reaction producing unwanted carbon deposits on methanation catalysts is a big challenge especially for the CO methanation but of minor importance for the CO2 methanation and therefore PtG applications.

In this paper, the applicability of methane decarbonization in the PtG concept has been analyzed on a general sense. Some development is still needed to put into practice this technology, mainly to improve from the laboratory scale to the demonstration and industrial scale. Hydrogen production rates should be up-scaled from a few mL/min to some ton/h with economically viable processes that could compete with existing hydrogen production processes, either from methane (as steam reforming) or electrolysis.

This chapter explores the potential of the PtG energy hub to participate in the ancillary service market. The two most important functions of the power grid ancillary services management are to: a.) balance generation output and load on the system on a continuous basis, and b.) adjust output from generator and sometimes also dropping download by management of consumption at end users. A simple techno-economic feasibility analysis of the PtG energy hub to offer regulation service in the ancillary service market has been carried out.

In 2012, the Advanced Research Projects Agency-Energy (ARPA-E) of the US Department of Energy issued a set of goals for NG storage (VED > 12.5 MJ/L). Of the four projects funded through the Methane Opportunities for Vehicular Energy program for development of new storage media, three involved the use of adsorbent materials. Of these sorbent-based projects, two focused on the application of advanced porous materials (metal-organic frameworks [MOFs] and porous organic polymers). MOFs comprise metal ions or atoms linked by multitopic organic linkers (independently referred to as secondary building units [SBUs]) to form extended two or three-dimensional porous materials, oftentimes with high crystallinity. The enormous variety in options involving organic and inorganic building unit selection gives rise to a plethora of possible structures with varying functionalities. The ability to tailor pore shapes and sizes, along with the presence of various functional groups has given rise to an incredible number of reports involving application of MOFs in fields such as gas storage, separations, catalysis, sensing, and drug delivery. The past several years have produced a surge in research investigating methane storage in MOFs, and have led to several quality review papers providing excellent insight into the status of MOFs for ANG technologies. As such, it is the purpose of this mini review to provide an overview of the adsorption of methane in MOFs with particular focus on identification and efficacy of adsorption sites.

Due to the undesirable effects of adsorption heat on the adsorptive storage vessels, these storage systems are not efficient enough to utilize in the automotive industry currently. Despite the research on various aspects of the adsorptive storage, it appears that thermal, and accordingly flow, management is substantially effective in improving the performance of this type of storage for gaseous fuels especially natural gas. Fundamental aspects of an ideal thermal management unit were explained in this chapter from a thermodynamic standpoint. Several thermal management approaches proposed and tested in the literature were discussed. It was demonstrated that the applying thermal management to an adsorptive storage system results in two major benefits, namely higher gas storage and shorter filling time.

This chapter discusses the properties and provides a brief history of these hydrates. Also, it discusses available options for the recovery of methane and the current Indian scenario in this field. The future global perspective has also been mentioned.